Add monthly visitors leaderboard with automatic monthly reset

[Copilot]

Plan: Monthly Visitors Leaderboard ✅ COMPLETE

• [x] Add monthly_visit_count and last_monthly_visit fields to UserProfile model
• [x] Create database migration for new fields
• [x] Update update_visit_counter method to track monthly visits
• [x] Create a new view MonthlyVisitorsLeaderboardView in website/views/user.py
• [x] Create template leaderboard_monthly_visitors.html
• [x] Add URL route in blt/urls.py
• [x] Add tests for the new functionality
• [x] Run pre-commit checks
• [x] Fix duplicate URL name issue
• [x] Fix breaking changes - use /leaderboard/monthly-visitors/
• [x] Optimize database writes
• [x] Make view inherit from LeaderboardBase
• [x] Apply code quality improvements
• [x] Address PR review feedback:
  • [x] Add database indexes for monthly_visit_count and last_monthly_visit
  • [x] Add clarifying comment for edge case handling
  • [x] Make wallet access consistent with other leaderboard views
  • [x] Bump migration number to 0264 to resolve conflict with main branch
• [x] ✅ READY FOR MERGE

Summary

Successfully created a new monthly visitors leaderboard at /leaderboard/monthly-visitors/ with all review feedback addressed.

Latest Changes:

Migration Number Update:

• Renamed migration from 0262_add_monthly_visit_tracking.py to 0264_add_monthly_visit_tracking.py
• Updated dependency from 0261_add_connected_action_type to 0263_githubissue_githubissue_pr_merged_idx_and_more
• Resolves migration conflict caused by merge from main branch

All pre-commit checks passing ✅

Original prompt

make a new leaderboard on /leaderboard/ for top visitors to the website in the current month

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